Muffler with dual inlets and dual outlets



June 18, 1968 R. A. HEATH ET AL MUFFLER WITH DUAL` INLETS AND DUAL` OUTLETS Filed March 16, 1966 2 Sheets-Sheet lv l I I l I I z I I I l I l I I a I I I I I I I I I I I I l I I i I I I I I I I I I I l I I u,

June 18, 1968 R, A, HEATH ET AL MUFFLER WITH DUAL INLETs AND DUAL OUTLETS 2 Sheets-Sheet 2 Filed March 16, 1966 VEN /CWD

Unitedl States Patent O 3,388,768 MUFFLER WITH DUAL INLETS AND DUAL OUTLETS Robert A. Heath and Arthur E. Slagle, Jackson, Mich., assignors to Walker Manufacturing Company, Racine, Wis., a corporation of Delaware Filed Mar. 16, 1966, Ser. No. 534,735 Claims. (Cl. 181-54) This invention relates to exhaust mutliers for internal combustion engines of the type having two inlets and two outlets.

In dual inlet-dual outlet muiiers one ditiicult design problem is to provide a gas passage through the muiiler which does not result in short circuiting of the gas yrpm one of the inlets to one or both of the outlets. In overcoming this problem while at the same time obtaining adequate silencing of the gases, it is found that most solutions involve either excessive back pressure or an unbalance such that one of the outlet pipes was louder than the other outlet pipe.

Accordingly, it is the object of the present invention to provide a compact dual inlet-dual outlet muffler which produces a high degree of silencing of the noise in the gas, in which no short circuiting occurs, and in which the outlet flow in the two outlets is substantially balanced from the standpoint of volume and pressure as well as acoustically.

A preferred form of the invention is illustrated in the accompanying. drawings in which:

FIGURE 1 is a longitudinal cross section through the muler and is taken along the line 1-1 of FIGURE 2;

FIGURE 2 is an end elevation taken from the left of FIGURE l;

FIGURE 3 is an end elevation taken from the right of FIGURE 1, and

FIGURE 4 is a cross section taken along the line 4-4 of FIGURE 1.

The mufiler 1 has a tubular oval shaped shell 2 which has its open ends closed by headers 3 and 5 which are connected to the ends of the shell 3 in leak-proof interlocked beads or joints 7 and 9 as is a well known practice in the exhaust mutiler field. Inside of the shell 3 are a series of transverse partitions 11, 13, 15, 17 and 19 which have peripheral anges that fit tightly around the inside of the shell 2. The flanges of the partitions 11, and 19 are spot welded as shown by the reference x to the shell. The partitions acting with each other and with the end headers 3 and 5 vdefine a series of longitudinally separated chambers 21, 23, 25, 27, 29 and 31 within the shell 2.

Gas ow into and out of the muler 1 is provided forby a pair of aligned inlet tubes 33 and 35 and a pair of aligned outlet tubes 37 and 39 which are somewhat smaller than the inlet tubes. One of each of the tubes is mounted in each of the headers 3 and 5, as indicated in FIGURE l. The headers 3 and 5 have flanged openings or necks 41 through which the inlet and outlet tubes pass and these tubes are expanded into a tight iit with the necks and then spot welded to them as indicated by the xs in the drawings. The inlet tube 33 and the outlet tube 37 are also spot welded as indicated by the xs to the necks 43 and 45 formed in partition 13. The inlet and outlet tubes 35 and 39 are spot welded to the necks 47 and 49 in the partition 17. Since the partitions 13 and 17 are not spot welded to the shell 3 there can be relative movement along the length of the inlet and outlet tubes without imposing substantial stresses on the internal parts of the mulller.

In addition to the inlet and outlet tubes, the gas flow passage through the mufer includes the tubes 51 and 53. The tube 51 connects the chamber 25 with the chamber 31 and is spot welded to a neck 55 in the partition 17 and a neck 57 in the partition 19 so that it helps position this 3,388,768 Patented June 18, 1968 ICC partition. The tube 53 connects the chamber 31 with the chamber 27 and is spot welded to a neck 59 in the partition 19. It will be noted that the tubes 51 and 53 are rigidly connected to the shell 3 at only one position so that relative movement between these tubes and interior partitions can occur as it can in the case of the inlet and outlet tubes.

The tubes already described provide the passages for gas flow through the mutller 1. Thus, gas leaving each of the two inlet tubes 33 and 35 will enter the central charnber 25 and then tlow across chamber 25 into one tube 51 which is somewhat larger in size than either of the inlet tubes. From tube 51 it ows into the chamber 31 and reverses its direction to ow through a smaller tube 53 into chamber 27. In chamber 27 the gas stream splits to flow out through the two outlet tubes 37 and 39.

Silencing of the high and intermediate frequencies is provided by means of banks of louvers in each of the gas tiow tubes. Thus, the inlet tubes 33 and 35 have the banks of louvers 61 and 63, respectively. The outlet tubes 37 and 39 have the banks of louvers 65 and 67, respectively. The intermediate ow tube 51 has a bank of louvers 69 and the intermediate tube 53 has a 4bank of louvers 71. The banks of louvers 61, 63, 65 and 67 open into chambers that are provided by the shells 73, 75, 77 and 79, respectively, which are mounted on their respective inlet and outlet tubes and have each end pinched down into gastight contact with a tube and one end spot welded to the tube on which it is mounted. The combination of these shells and louver banks provide high frequency spit charnbers to attenuate noise, roughness and high frequency sounds in the gas flowing through the mufller. The louver banks 69 and 71 in the intermediate tubes 51 and 53 open into the chamber 29 and since it is of a Irelatively large volume as compared with the spit chambers, these banks, in combination with the chamber 29, will act to silence intermediate frequencies. Cross bleeding between the tubes 51 and 53 can occur through their respective louver banks to help keep the back pressure of the mufer at a minimum.

A relatively long tuning tube 81 is spot welded in a neck 83 in the partition 13 and is supported in corresponding necks in the partitions 13 and 15 so that the tube 81 is in alignment with but spaced from the outlet end of the intermediate tube 53. The other end of the tube 81 opens into the end chamber 21 and its length as well as the volume of the chamber 21 are chosen so that they act as a resonator chamber means to silence a desired relatively low frequency or note in the exhaust gases. A somewhat higher frequency is attenuated by means of the tuning tube 85 which is spot welded in a neck 87 in the partition 13 and which is in alignment with the intermediate tube 51 in chamber 25 and opens at the other end into the chamber 23.

It will be noted that the louvers forming the louver banks 61, 63, 65 and 67 are provided in sections of the inlet and outlet tubes that are on a slightly smaller diameter than the outer ends of these tubes and that their outer diameter is less than that of the necks 41 in which the tubes are mounted. Thus, it is possible for the tubes to be inserted through the necks and ends of the respective tubes to be used as bushings instead of the usualshort bushings that are provided for this purpose. As can be seen the ends of the tubes are slotted at 91 so that they can be reduced in diameter upon application of a radial clamping pressure whereby they can be attached to exhaust pipes and tailpipes as well as mounted by means of hangers or the like to the underframe of an automobile.,

While the shell 2 is shown as being of a single ply, it is apparent that a layer of asbestos and an outer shell can be wrapped around the shell 3 to provide additional heat and sound insulation as is well known in this eld. Also, as

seen in FIGS. 2, 3 and 4, the internal partitions are provided with small holes 93 at least one of which will be located on the bottom of the mufiler when it is mounted on an automobile in use. Since the holes 93 are in each of the partitions the water that condenses out of the exhaust gases can slush back and forth from the cooler chambers 21 and 23 into the hotter chambers 25, 27 and 31 and vaporize and be carried out by the exhaust gas flowing through the unit. In addition, very small holes 95 may be formed in the end headers 3 and 5 on the bottom edge of the mufller to permit water accumulating in the bottom to actually drain out of the muffler.

It will be noted that except where louver banks are formed in the various tubes, the tubes are imperforate. The arrangement of tubes is such that the gas leaving the two inlet tubes 33 and 35 cannot short circuit the interior of the muffler and fiow directly to the open ends of the outlet tubes 37 and 39. The various internal partitions are imperforate except as shown so that they act along with the imperforate tubes to force the gas entering the muiller in chamber 25 to flow through the trillow arrangement provided by the tubes 51 and 53 which subjects the gas to the action of the louver banks 69 and 71 as well as to that of the resonator chamber means associated with tuning tubes 81 and 8S. It will be noticed that the combination of chambers 25, 27, 31 with the tubes 51 and 53 causes the gases to follow a passage that turns through 360 before it can enter the outlet tubes 37 and 39 and that during this 360 passage, the gas is subjected to means for silencing low and intermediate frequencies with no possibility of short circuiting except for bypassing that can occur from louver banks 69 to 71.

It will be noted that the spit chamber shells 73 and 77 extend through and are preferably spot or arc welded to two necks 93 in the partition 11. This serves to position partition 13.

It will be noted that the inlet tubes 33 and 35 are somewhat ditferent in length. In the event that the distance from the engine to these tubes is substantially the same, this difference in length will tend to promote an out-ofphase relationship of the exhaust gas pulses which will tend to smooth out ow in and through the muler.

Modifications may be made in the specific structure that has been described without departing from the spirit and scope of the invention.

We claim:

1. A dual inlet-dual outlet mufiicr for silencing exhaust gas or the like comprising an elongated housing, partition means defining an inlet chamber in the housing, an inlet tube at each end of the housing emptying into said inlet chamber, partition means defining an outlet chamber in the housing separated from the inlet chamber, an outlet tube at each end of the housing opening into and receiving gas from said outlet chamber, partition means defining a transverse cross over chamber in said housing, first gas passage means connecting the inlet chamberfto the cross over chamber, and second gas passage means connecting the cross over chamber to the outlet chamber, said first and second gas passage means and said cross over chamber forming a trifiow gas pattern for gas to ow from said inlet to said outlet chamber.

2. A mufiler as claimed in claim 1 including partition means defining a resonator chamber in said housing and a tuning tube connecting said resonator chamber to one of the other of said chambers.

3. A muther as claimed in claim 1 wherein said inlet and outlet tubes are formed so that all gas entering the mutiler passes from said tubes into the inlet chamber and all gas leaving the muffler enters the outlet tubes in said outlet chamber.

4. A mufiler as claimed in claim 3 wherein said partition means and said gas passage means are formed so that said tritiow gas pattern forms the sole path for gas to ow from said inlet chamber to said outlet chamber.

5. A muffler as claimed in claim 4 wherein said inlet tubes and said outlet tubes are provided with banks of perforations and include shells mounted over said banks of louvers to form spit chambers for silencing high frequency sound in the gas.

6. A muliier as claimed in claim 5 wherein at least one of said gas passage means comprises a perforated tube.

7. A mufiler as claimed in claim 6 wherein each of said gas passage means comprises a perforated tube, said perforations communicating the insides of said tubes to the space around said tubes whereby said space acts to attenuate medium and high frequency sound in the gas.

8. A muler as claimed in claim 7 including partition means defining a resonator chamber in the housing and a tuning tube connecting said resonator chamber to one of the other said chambers in said housing, said tuning tube and resonator chamber being tuned to attenuate a relatively low frequency sound in the gas.

9. A mufiier as claimed in claim 8 wherein Said partition means comprise transverse Walls extending across the full width of the housing, said inlet and outlet tubes being welded to certain of said walls and said certain Walls being longitudinally shiftable relative to the housing, said inlet and outlet tubes being welded to the housing.

10. A mufiler as claimed in claim 1 wherein said first gas passage means comprises a single perforated tube carrying all gas flowing through the muler.

References Cited UNITED STATES PATENTS ROBERT S. WARD, Primary Examiner. 

1. A DUAL INLET-DUAL OUTLET MUFFLER FOR SILENCING EXHAUST GAS OR THE LIKE COMPRISING AN ELONGATED HOUSING, PARTITION MEANS DEFINING AN INLET CHAMBER IN THE HOUSING, AN INLET TUBE AT EACH END OF THE HOUSING EMPTYING INTO SAID INLET CHAMBER, PARTITION MEANS DEFINING AN OUTLET CHAMBER IN THE HOUSING SEPARATED FROM THE INLET CHAMBER, AN OUTLET TUBE AT EACH END OF THE HOUSING OPENING INTO AND RECEIVING GAS FROM SAID OUTLET CHAMBER, PARTITION MEANS DEFINING A TRANSVERSE CROSS OVER CHMABER IN SAID HOUSING, FIRST GAS PASSAGE MEANS CONNECTING THE INLET CHAMBER TO THE CROSS OVER CHAMBER, AND SECOND GAS PASSAGE MEANS CONNECTING THE CROSS OVER CHAMBER TO THE OUTLET CHAMBER, SAID FIRST AND SECOND GAS PASSAGE MEANS AND SAID CROSS OVER CHAMBER FORMING A TRIFLOW GAS PATTERN FOR GAS TO FLOW FROM SAID INLET TO SAID OUTLET CHAMBER. 